Visual Basic Rises Again as a Document Malware Scripting Language
With a nod to the past success of macro viruses, more than one-quarter of all document malware now spreads via Microsoft's Visual Basic scripting language.In July 1995, a proof-of-concept macro virus, fittingly known as "Concept," started infecting Microsoft Word documents using a Visual Basic script to copy itself to the default template file. For six years after that, macro viruses written in Visual Basic for Applications (VBA) dominated the rogues gallery of malicious software, supplanting boot-sector viruses as the top method of propagating code. And then, in 2001, the technique became nearly extinct, as Internet worms became the favored infection method. Now, document malware written in Visual Basic is once again on the rise, according to an analysis by researchers at security firm Sophos. Macro-based infectors accounted for 28 percent of all document malware in July 2014, up from 6 percent the previous month. The rise in usage is likely due to common macro templates being shared between criminal groups, Sophos researcher Graham Chantry said in an email statement to eWEEK. "Up until now we could only speculate as to why authors moved towards VBA, but these templates would go some way to explaining it," he said. "Getting malware installed on a user’s machine is one of the most difficult parts of the infection process, and with some companies explicitly blocking executable attachments, a VBA template ... provide(s) the perfect solution."
Like the macro viruses of the past, a significant number of current malware threats used Visual Basic to encode functionality within documents. In the mid-1990s, the success of Concept in the mid-1990s gave birth to a litany of similar viruses that used the lack of anti-malware technology to spread quickly through email attachments.